1. Field of the Invention
The present invention relates to audio bass enhancement, and more particularly, to an apparatus and a method for audio base enhancement, which use the fact that a baseband signal output from two speakers is recognized as if the signal is output from one sound source when the distance between the speakers is short.
2. Description of the Related Art
Speakers are acoustic devices which radiate audio waves by generating longitudinal waves in the air by changing an electrical signal into vibrations of a vibrating plate. The speakers only reproduce a signal within a predetermined frequency range due to their structural characteristics. That is, speakers can only reproduce an input electrical signal corresponding to a predetermined frequency reproduction band into an undistorted signal. The minimum reproduction frequency corresponding to the frequency reproduction band is the lowest frequency at which sound can be reproduced without distortion within the frequency reproduction band.
Thus, in order to reproduce low frequency bass signals, speakers must be designed so that the minimum reproduction frequency is low. In order to lower the minimum reproduction frequency of speakers, speakers must have a large-caliber vibrating plate and be thick enough to ensure sufficient amplitude of the output bass signal.
However, due to a trend towards light, thin, and miniaturized electronic products, the size of speakers for generating sound from various acoustic products has gradually been miniaturized. Also, installation space of speakers has been reduced. Thus, for micro speakers used in mobile phones, portable multimedia devices, and headphones, only speakers whose bass reproduction limit frequency is around a few hundreds of hertz (Hz) are produced due to the size limitation of the micro speakers. However, since the human-audible band is conventionally from 20 Hz to 20,000 Hz, a non-reproducible band of base sound corresponding to a frequency range from 20 Hz to a few hundreds of Hz, that is, the bass reproduction limit frequency, exists in micro speakers. Due to the structural limitations of the micro speakers, audiences only hear a relatively plain sound in which deep and rich audio bass is not included.
To solve the problem described above, a method of reproducing audio bass using psychoacoustics has been developed. However, a complicated operation is required to realize the method. As a result, adoption of the method is determined according to capabilities of a digital signal processor (DSP) of a product in which the method is to be adopted.